(a) Additions in the amount of insurance, up to the allowable limits, may be made at any time by the subscriber by submitting a written statement to the board or to any of its agents except during a period when a claim filed by the subscriber is open and pending investigation by the department. Upon receipt of the subscriber's written statement by the board or any of its agents, the board shall have sixty days from the day the request was received to reinspect the structure. If reinspection occurs within the sixty-day period and the structure passes the reinspection, the new amount of insurance shall be effective from the date of premium payment after reinspection. If reinspection does not occur within the sixty-day period, the new amount of insurance shall be effective from the date the subscriber's written request for additional insurance was received by the board or any of its agents, but the additional coverage will be null and void if the applicant fails to remit the premium payment within twenty days from the day the bill for additional premium is postmarked.

(b) The additional insurance may be subjected to later reductions, and premiums adjusted accordingly, if the board determines that the added insurance raises the total amount of insurance in excess of the current replacement cost of the structure or the maximum amount of coverage established by the fund, whichever is less.

(c) The additional insurance shall be void if, upon reinspection of the structure, the board determines that either: